Gordon Brown has "the most enormous personal regard" for media magnate Rupert Murdoch, Downing Street said today amid reports that the prime minister telephoned him directly to complain about the Sun's criticism of his government's handling of the war in Afghanistan.

The pair spoke on Tuesday at the height of a row over Brown's misspelling of a dead soldier's name in a handwritten letter of condolence to the victim's grieving mother Jacqui Janes, published by the newspaper alongside her accusations of disrespect.

In September, the Sun switched its allegiance from Labour to the Conservatives after 12 years, choosing the night of Brown's keynote speech to his party conference to announce its decision.

Lord Mandelson accused the Sun yesterday of "bad taste and crude politicking" as relations with the best-selling daily, already strained by the newspaper's decision to ditch Labour, boiled over publicly.

No 10 refused to discuss the conversation between Brown and Murdoch, revealed in the Financial Times, and attempted to play down the significance of the call, saying the two were in regular communication.

"He has regular communications with Rupert Murdoch, as you would imagine, and he has the most enormous personal regard for Rupert Murdoch," the prime minister's official spokesman said.

"I am not going to give any further information about the conversation. I am commenting as much as I think I can about a personal conversation. There is nothing unusual in the prime minister talking to Rupert Murdoch."

Asked what in particular he liked about the News Corp chairman, the spokesman said: "What he has done as an international businessman – his record speaks for itself."

The chairman and chief executive of News Corporation, owner of papers including the Times and the Sun said this week that Brown was a friend who had been unlucky as prime minister.